A critical letter sent to federal health officials by 33 hospitals— including three in the Twin Cities — has created a buzz among some who see it as evidence that a key element of the health care law is showing cracks.

Allina Health, Fairview Health Systems and Park Nicollet Health Services are among those questioning the standards used in a pilot program in which providers get paid based on the quality of care, not merely how many patients they see.

The health care organizations, which are taking part in a federal health reform pilot project, raised concerns about unreasonable standards in a Feb. 25 letter to the Center for Medicare and Medicaid Innovation.

The hospitals say they want another year to work on the benchmarks to make them more fair.

Some critics of the federal health care law seized on the letter, which was first reported by Inside Health Policy. The trade journal construed the letter as a threat by the hospitals to drop out of the pilot program.

“This is what a federally run delivery system reform actually looks like: a lot of failure and frustration,” wrote Peter Suderman of Reason magazine, in a blog post. “And it’s why we should be skeptical that modest reforms will ever be enough.”

Several hospital officials countered that the letter was a normal part of give-and-take in any pilot program.

“We believe we’ll work it out,” said Allina Health’s Patrick Flesher. “We’re learning. Everybody I’ve talked to is very committed to the program.”

The hospitals are among a group hand-picked by the federal government to take part in a Medicare test project to create accountable care organizations, or ACOs. The ACOs have been heralded for their potential to reduce the nation’s skyrocketing spending on health care.

As the name suggests, the health systems would be held accountable — and reimbursed — for how well they care for patients. That’s a departure from the current fee-for-service payment system, where doctors get paid by Medicare every time they perform a treatment.

Flesher, who directs the Pioneer ACO program at Allina, described the concerns as a “blip that came up recently,” and that hourlong meetings with federal officials have been “very collaborative.”

“We’re not saying we don’t want to be measured on quality,” he said. “We want a fairer way to measure.”